Title

Asteroid 21 Lutetia at 3μm: Observations with IRTF SpeX

Document Type

Article

Publication Date

11-1-2011

Abstract

We present observations of Asteroid 21 Lutetia collected 2003-2008 using the SpeX instrument on the NASA Infrared Telescope Facility (IRTF) covering 2-4 μm. We also reevaluate NSFCam observations obtained in 1996 (Rivkin, A.S., Lebofsky, L.A., Clark, B.E., Howell, E.S., Britt, D.T. [2000]. Icarus 145, 351-368). Taken together, these show deeper 3-μm band depths (of order 3-5%) in the southern hemisphere of Lutetia, and shallower band depths (of order 2% or less) in the north. Such variation is consistent with observations at shorter wavelength by previous workers (Nedelcu, D.A. et al. [2007]. Astron. Astrophys. 470, 1157-1164; Lazzarin, M. et al. [2010]. Mon. Not. R. Astron. Soc. 408, 1433-1437), who observed hemispheric-level variations from C-like spectra to X-like spectra. While the shallowness of absorption bands on Lutetia hinders identification of its surface composition, goethite appears plausible as a constituent in its southern hemisphere (Beck, P., Quirico, E., Sevestre, D., Montes-Hernandez, G., Pommerol, A., Schmitt, B. [2011]. Astron. Astrophys. 526, A85-A89). Mathematical models of space weathered goethite are most consistent with Lutetia's southern hemisphere spectrum, but more work and further observations are necessary to confirm this suggestion. © 2011 Elsevier Inc.

Publication Name

Icarus

Volume Number

216

First Page

62

Last Page

68

Issue Number

1

DOI

10.1016/j.icarus.2011.08.009

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